The objective of this project is to obtain a better grasp on the nature and time course of neurobehavioral changes which ensue following cigarrette smoking cessation. These effects are to be studied both under controlled conditions where the performance and status of abstaining smokers on a variety of behavioral tasks and physiological indices can be carefully measured following abrupt withdrawal, and under more naturalistic conditions using survey techniques to track broad behavioral changes in participants of quit-smoking clinics who are withdrawing on varied schedules. The aim of this two-part study is to provide empirical data addressing the nature and time course of the smoking withdrawal syndrome, and significance of these effects in relation to proficiency in daily activities and performance of former smokers. Major emphasis in this research is on the short term (0-9hr.) effects of smoking deprivation as nicotine is excreted from the body, and the long term (greater than 2 weeks) reactions experienced by ex-smokers.